The containers for containing liquid contents must be capable of favorably discharging the contents irrespective of the materials forming the containers. Discharging the content is not almost of a problem when the liquids having low viscosities such as water and the like are contained. Discharging the content, however, becomes a serious problem when the content is a highly viscous substance such as mayonnaise or ketchup irrespective of the plastic container or the glass container. Namely, the contents of this kind are not quickly discharged despite the container is tilted. Besides, the contents tend to stay on the container wall and cannot be all recovered. Particularly, the content stays in considerable amounts on the bottom of the container and is not all recovered.
In recent years, there have been proposed various kinds of technical arts for improving slipping properties to viscous substances by forming an oil film on the surfaces of the formed bodies such as containers and the like (e.g., see patent documents 1 and 2).
According to the above technical arts, the slipping property can be strikingly improved as compared to the cases of adding an additive such as lubricant to the synthetic resin that forms the surfaces of the formed bodies, and attention has now been paid thereto.
According to the above means for improving surface properties by forming the oil film on the surfaces of the base materials as described above, however, the life for effectively exhibiting the slipping property relying on the oil film does not last long. After the passage of long periods of time, therefore, the slipping property decreases and, depending upon the cases, the content adheres to the surfaces. This tendency becomes conspicuous particularly when the substance that falls down along the surface is an emulsified product or, specifically, mayonnaise-like food containing little oil components.
The present applicant has previously proposed a packing container for containing oil-in-water type emulsified products as represented by mayonnaise-like foods, the packing container having an oil film formed on the inner surface thereof that comes in contact with the oil-in-water type emulsified products (Japanese Patent Application No. 2014-023425).
The present applicant has also previously proposed a packing material having a liquid film formed on the inner surface thereof that comes in contact with the content, the liquid film being dispersed with solid particles of a grain size of not larger than 300 am (Japanese Patent Application No. 2014-126877).
However, even the above arts previously proposed by the present applicant are not still effectively solving the problem of a decrease in the slipping property with the passage of time.